云南松林资源动态研究

Dynamic of Pinus yunnanensis Forest Resources in Yunnan

利用云南省森林资源监测数据对云南松林资源的动态变化进行了研究,结果表明:在1987—2007年的20 a间,云南松林资源总体呈增长趋势,尤其是蓄积量在1997—2002年得益于天然林保护工程,出现了快速上升,5 a净增20.57%,与此同时,过熟林资源一直处于较低水平,优质可用云南松林资源的数量持续减少,濒临枯竭。云南松林分单位面积蓄积量20 a间提高了27.05%,而大径组和特大径组林木蓄积所占比例则呈下降趋势,近、成、过熟林的单株材积从每株0.77 m3降至0.22 m3,表明云南松林质量在总体上提高的同时,可用资源数量仍在快速减少,材种结构低质化倾向加剧。云南松林分林龄结构一直呈现出显著的低龄化特征,林龄结构现状迫切要求加强对云南松林的抚育管理,科学开展森林经营。20 a间,云南松林主导利用方向波动较大,难以实现长期经营目标。监测期间,以保护为主导的森林经营政策使云南松林资源得到了休养生息,但仍然存在着粗放经营、经营目标随意调整和对成过熟林资源过度利用等森林经营管理问题,这些因素相互交织,成为云南松林资源数量、林分质量和林龄结构变化的主要原因。

In order to understand the dynamic change and provide decision basis for sustainable management of Pinus yunnanensis forest resource in Yunnan Province,monitoring data obtained by continuous forest inventory during 1987-2007 was analyzed by applying mathematical statistics and chart analysis methods. Based on the analysis of variation of the forest areas, stock volume, quality and structure, the dynamic variation rule of the forest was revealed with plenty of detailed data from various angles. The result show that the resources of the forest continue to grow during 1987-2007, and the growing rate was increased rapidly during 1997- 2002, when the Natural Forest Protection Project had been implemented(the total stock volume of the forest increased from 20462.33×104m3to22243.65×104m3, which is over 20.57% in five years time). On the same time, however, the percentage of over-mature Pinus yunnanensis forest was relative low and the stock volume of high quality, available resources of the forest continuously decline, and was close to exhaustion. The result also shows that the unit area stock volume of the forest had increased27.05% in 20 years, while the volume of large or super-large timber showed a descending tendency in this period, especially the percentage of super- large timber decreased from19.9% to 6.8%, being only the 1/3 of the original. The stock volume of the individual plant in near-mature, mature and over-mature forest fell to 0.22 m3 from 0.77 m3, which indicated that the resources available for logging were decreasing rapidly, and the tendency of poorer quality of timber structure was exacerbated while the general quality of the forest was improved. The age structure of Pinus yunnanensis forest in Yunnan Province show a remarkable characteristic of lowering ages trend, and this highlighted the importance of nursing and scientific management of the forest. The analysis also showed that the variation of dominant utilization types of Pinus yunnanensis forest in 20 years was significantly adverse to the effective management of the forest. The Pinus yunnanensis forest rehabilitated during monitoring period benefited from the protection- oriented policy, however, the management of the forest still presented problems, such as extensive management, randomly regulation of management objective and over-use of mature and over-mature forest resources etc., and the interaction of the above mentioned problems led to the fluctuation of resources quantity, stand quality and the age structure of Pinus yunnanensis forest in Yunnan Province.